To evaluate the prognostic value of measuring heart rate variability (HRV) in horses with colic at the time of admission to a referral hospital.
51 horses > 1 year of age with colic (41 that survived [survivors] and 10 that died or were euthanized [nonsurvivors]).
HRV was recorded within 1 hour after admission by use of heart rate sensors with horses restrained in stocks. A 5-minute recording period was analyzed to obtain HRV measurements (eg, SD of R-R intervals [SDRR], root mean square of successive differences between R-R intervals [RMSSD], and geometric SDs determined from Poincaré plots [SD1 and SD2]). Variables associated with outcome (survival vs nonsurvival) were identified. Measurements were compared among diagnostic categories for colic (obstructive, inflammatory, or ischemic).
SDRR and RMSSD were significantly higher in survivors (median [25th to 75th percentile], 91.0 milliseconds [78.9 to 114.6 milliseconds] and 64.8 milliseconds [40.9 to 78.4 milliseconds], respectively) than in nonsurvivors (50.7 milliseconds [29.1 to 69.2 milliseconds] and 33.4 milliseconds [12.6 to 47.9 milliseconds], respectively). Similarly, SD1 and SD2 were significantly higher in survivors (48.3 milliseconds [28.9 to 60.9 milliseconds] and 111.3 milliseconds [93.0 to 146.6 milliseconds], respectively) than in nonsurvivors (23.7 milliseconds [8.9 to 33.9 milliseconds] and 65.1 milliseconds [33.7 to 91.9 milliseconds], respectively). The SDRR and SD2 were significantly higher for horses with obstructive colic than for horses with ischemic colic.
CONCLUSIONS AND CLINICAL RELEVANCE
Analysis of HRV in horses with colic may provide information on the underlying cause and be helpful in identifying horses less likely to survive.
OBJECTIVE To evaluate horses with atrial fibrillation for hypercoagulability; plasma D-dimer concentrations, as a marker of a procoagulant state; and a relationship between coagulation profile results and duration of atrial fibrillation or presence of structural heart disease.
DESIGN Case-control study.
ANIMALS Plasma samples from 42 horses (25 with atrial fibrillation and 17 without cardiovascular or systemic disease [control group]).
PROCEDURES Results of hematologic tests (ie, plasma fibrinogen and D-dimer concentrations, prothrombin and activated partial thromboplastin times, and antithrombin activity) in horses were recorded to assess coagulation and fibrinolysis. Historical and clinical variables, as associated with a hypercoagulable state in other species, were also recorded.
RESULTS Horses with atrial fibrillation and control horses lacked clinical signs of hypercoagulation or thromboembolism. Compared with control horses, horses with atrial fibrillation had significantly lower antithrombin activity. No significant differences in plasma fibrinogen and D-dimer concentrations and prothrombin and activated partial thromboplastin times existed between horse groups. In horses with atrial fibrillation versus control horses, a significantly larger proportion had an abnormal plasma D-dimer concentration (10/25 vs 2/17), test results indicative of subclinical activated coagulation (18/25 vs 6/17), or abnormal coagulation test results (25/121 vs 7/85), respectively.
CONCLUSIONS AND CLINICAL RELEVANCE Horses with atrial fibrillation did not have clinical evidence of a hypercoagulable state, but a higher proportion of horses with atrial fibrillation, compared with control horses, did have subclinical activated coagulation on the basis of standard coagulation test results.
To assess the prevalence of exercise-induced pulmonary hemorrhage (EIPH) among elite endurance horses after competition in a long-distance race.
20 endurance horses and 12 nonexercised or minimally exercised age-, breed-, and trainer-matched horses from the same environment (control horses).
Bronchoalveolar lavage fluid samples collected from endurance horses at 3 to 8 days (sample A) and 36 to 38 days (sample B) after the race (100 km in 1 day [n = 3], 70 km/d for 2 days , or 100 km/d for 2 days ) were cytologically examined for the presence of hemosiderophages. Samples from control horses were collected at the same time as sample B was obtained from respective matched endurance horses and similarly examined. Horses with bronchoalveolar lavage fluid samples in which > 1% of identified cells were hemosiderophages were considered to have evidence of EIPH.
Of 20 endurance horses, 9 (45%; 95% confidence interval, 25% to 66%) and 10 (50%; 95% confidence interval, 29% to 71%) had cytologic evidence of EIPH in samples A and B, respectively. Evidence of EIPH was present in 6 of 20 (30%) horses at both sample collection times, 3 (15%) at the first sample time only, and 4 (20%) at the second sample time only. In contrast, 1 of 12 control horses had cytologic evidence of EIPH.
CONCLUSIONS AND CLINICAL RELEVANCE
The prevalence of EIPH in these elite endurance horses (45% to 50%) was higher than previously reported estimates for poor-performing endurance horses; however, differences in criteria for identification of EIPH should be considered when comparing findings between studies.
Objective—To compare results of intradermal tests
(IDT), conducted using environmental allergens, in
horses without atopy and horses with chronic
obstructive pulmonary disease (COPD).
Animals—38 horses (22 horses without atopy and 16
horses with COPD).
Procedure—All horses were examined (physical
examination, hematologic examination, serum biochemical
analyses, examination of bronchoalveolar
lavage fluid). An IDT was conducted, using a full panel
of 73 allergens consisting of grasses, weeds, trees,
molds, and insects. Results of the IDT were evaluated
30 minutes and 4, 6, and 24 hours after injection
of allergens. Horses without atopy were euthanatized,
and gross and histologic changes of lung
parenchyma were assessed.
Results—Horses without atopy had a greater number
of positive immediate and late-phase reactions than
did horses with COPD. Horses with COPD did not
have a significantly greater number of positive reactions
than horses without atopy at any time period for
any allergen group (grasses, weeds, trees, molds,
Conclusions and Clinical Relevance—Positive
results of IDT document allergen-specific hypersensitivity
but do not necessarily distinguish clinically relevant
reactions from subclinical reactivity in horses
with COPD. Interpreting the clinical relevance of
results of IDT requires a thorough knowledge of the
medical history, physical examination findings, and
environment of each animal. (Am J Vet Res
Objective—To clone and sequence cDNA for equine
insulin-responsive glucose transporter (glucose transporter
type 4 [GLUT-4]) and determine effects of
glycogen-depleting exercise and meal type after exercise
on GLUT-4 gene expression in skeletal muscle of
Animals—Muscle biopsy specimens
from 7 healthy adult horses.
Procedure—Total RNA was extracted from specimens,
and GLUT-4 cDNA was synthesized and
sequenced. Horses were exercised on 3 consecutive
days. On the third day of exercise, for 8 hours after exercise,
horses were either not fed, fed half of daily energy
requirements as hay, or fed an isocaloric amount of
corn. The GLUT-4 mRNA was determined by use of realtime
reverse transcriptase-polymerase chain reaction in
muscle biopsy specimens obtained before 3 consecutive
days of exercise and within 10 minutes and 4, 8,
and 24 hours after the third exercise bout.
Results—A 1,629-bp segment was sequenced, of
which 1,530 bp corresponded to the coding region
and encoded a protein of 509 amino acids.
Expression of GLUT-4 gene increased by 2.3, 4.3, 3.3,
and 2.6 times 10 minutes and 4, 8, and 24 hours after
exercise, respectively, compared with that prior to
exercise. No differences were observed in GLUT-4
gene expression among conditions of feed withholding,
corn feeding, and hay feeding during the 8 hours
Conclusions and Clinical Relevance—Lack of
increase of GLUT-4 gene expression after grain feeding
and exercise may explain the apparently slower rate of
glycogen synthesis after exercise in horses relative to
that of other species. (Am J Vet Res 2005;66:379–385)
Objective—To compare responses to a variety of
intradermally injected allergens among healthy horses
and horses with chronic obstructive pulmonary disease
(COPD), recurrent urticaria (RU), and atopic dermatitis-insect hypersensitivity (allergic dermatitis
Procedure—Results of intradermal testing for horses
with COPD, RU, or AD were compared with results
for healthy horses.
Results—Compared with healthy horses, horses with
COPD, RU, and AD were significantly more likely to
have positive (≥ 3+) reactions to intradermal allergens
(molds, weeds, trees, grasses-crops, and insects) 30
minutes (immediate reaction), 4 hours (late-phase
reactions), and 24 hours (delayed-phase reactions)
after exposure. In addition, diseased horses reacted
to a significantly higher number of allergens in each
allergen group than did healthy horses.
Conclusions and Clinical Relevance—Reactions to
individual allergens should not be used to determine
that horses have hypersensitivity. Overall patterns of
reactivity to intradermal allergens may be helpful in
management when used in conjunction with a compatible
history and evidence of potential exposure to
allergens in horses with conditions associated with
hypersensitivity to environmental allergens. (J Am Vet
Med Assoc 2001;62:1115–1121)
Objective—To determine the impact of successive days of endurance exercise on select serum chemistry values in conditioned Alaskan sled dogs.
Design—Prospective cohort study.
Animals—10 conditioned Alaskan sled dogs.
Procedures—All dogs ran 160 km/d for 5 consecutive days. Serum was obtained prior to exercise and immediately after each exercise run; all samples were obtained before dogs were fed. Serum electrolyte, mineral, protein, total bilirubin, urea nitrogen, creatinine, and cardiac troponin-I concentrations and serum alkaline phosphatase, alanine aminotransfer-ase, creatine kinase, and aspartate aminotransferase activities were measured. Data were analyzed by means of analysis of covariance for a randomized complete block design with dog as a blocking variable, time as a covariate, and distance run as the treatment of interest. Least square mean values were compared with values obtained prior to exercise, and linear and quadratic contrasts were examined.
Results—Serum globulin concentration was low prior to exercise (mean ± SD, 2.2 ± 0.3g/dL) and progressively decreased as exercise continued. Exercise was associated with increases in serum chloride, urea nitrogen, and cardiac troponin-I concentrations and serum alanine aminotransferase, creatine kinase, and aspartate aminotransferase activities and with pro-gressive decreases in serum potassium, total protein, and albumin concentrations.
Conclusions and Clinical Relevance—Results suggested that multiple successive days of endurance exercise resulted in mild aberrations in serum chemistry variables in conditioned sled dogs. Changes likely reflected the metabolic stresses of prolonged endurance exercise as well as dietary composition. Hypoglobulinemia in resting, conditioned sled dogs may reflect the immunosuppressive or catabolic effects of intense endurance training.